I tried that with more responses and it comes out that the number of additional ajax calls depends on the number of JSON objects contained in the response, which is a big problem when trees are more complex

I have a TreeStore with proxy of type ajax. Then I do a call with additional params to change the tree based on id:

myStore.load({params: {id: 'DS00001'}});

but I do not pass a node - I expect that the tree is refreshed from the server JSON response. After the initial load correctly one request is sent, but after invoking load() method I have multiple requests being sent to the server as described above.. What did you mean by passing a node? Node object, or some text identification of what will be the root node from the response?